Degradation of 2,4-dichlorophenol by nanoscale calcium peroxide: Implication for groundwater remediation

In this study, a newly emerging oxidant nanoscale calcium peroxide (nCaO 2 ) was synthesized to degrade 2,4-dichlorophenol (2,4-DCP). nCaO 2 was prepared from nanoscale Ca(OH) 2 and H 2 O 2 and confirmed to be less than 150   nm in diameter and 62.23   m 2   ·   g −1 in specific surface area (SSA). For treating 2,4-DCP, the optimal ratio between Ca(OH) 2 and H 2 O 2 was 1:5. Compared with conventional CaO 2 , nCaO 2 was found to be more efficient for destructing 2,4-DCP. 2,4-DCP was completely degraded in 5 d by nCaO 2 while only 75.0% 2,4-DCP was destructed by conventional CaO 2 . The effects of solution pH and water matrix, including SO 4 2− , HCO 3 − and humic acid (HA) were examined. The reactive species in nCaO 2 system was investigated by photoluminescence (PL) technique and the quenching experiments. Results showed that hydroxyl radical (OH ) was the dominant reactive species for destructing 2,4-DCP. The major oxidation products identified in this study were 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), phenol and benzoquinone (BQ). Our works gave an important insight into the use of nCaO 2 to degrade some organic contaminants which might provide some references for the application of nCaO 2 in chlorophenols contaminated groundwater remediation.